The present invention relates to an improved writing strategy for CD-RW, especially to an improved writing strategy for CAV (constant angular velocity) writing of CD-RW.
The writing strategy is important issue for CD-RW (compact disc rewritable), which is applied to renew, establish and store video and audio data. The CD-RW standards were developed to allow writing, erasing and rewriting data on various rewritable optical disk media. Thus, a CD-RW system should have a suitable writing strategy so as to be compatible with various rewritable optical disks made by different manufacturers.
In the CLV (constant linear velocity) writing mode, the writing speed is kept constant for both the inner radius and the outer radius of the optical disk. When a rewritable optical disk is placed into the CD-RW drive, a fixed duty ratio is set for the inner radius and outer radius of the optical disk. Afterward, the jitter values for various writing speeds are measured by a certain instrument to ensure the jitter values are below a threshold (for example, 35). The writing strategy for each writing speed of the CD-RW can be optimized in this way.
However, for the CAV (constant angular velocity) writing mode of the CD-RW, the writing speed is varied linearly from inner radius of the disk to the outer radius of the disk. For example, if the writing speed for inner radius is 4xc3x97 speed, the writing speed at the center radius is 8xc3x97 speed and the writing speed at the outer radius may be 10xc3x97 speed. When the rewritable optical disk is placed into a CD-RW system with CAV writing mode, the duty ratios for 4xc3x97, 8xc3x97 and 10xc3x97 writing speeds are set, respectively. Afterward, the jitter values for those writing speeds are measured to ensure the jitter values are within tolerance. However, the duty ratios for each region are often determined after repeated measurement. Thus, the optical disk is segmented into several regions of equivalent writing speed and then the writing strategy is optimized for each of those intervals. This approach is complicated and time consuming for CD-RW manufacturers, especially since the writing strategy may have to be modified for rewritable optical disks of different manufacturers.
It is the object of the present invention to provide an improved writing strategy for CAV writing of CD-RW media, which uses similar strategy as the CLV writing mode.
To achieve the above object, the present invention provides an improved writing strategy for CAV (constant angular velocity) writing of CD-RW media. First, a duty ratio is set and then a laser writing pulse duration is determined for this duty ratio. Afterward, the duty ratios for various writing speeds are deduced from the laser writing pulse duration.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: